1. Field of the Invention
The present invention relates to an apparatus for recording or reproducing digital information such as video and audio data, more particularly, to digital information recording and reproducing apparatus capable of setting a limit to playback or copying of the information to be recorded or reproduced by the authority of copyright holders and the like. Further, the present invention relates to a transmitting apparatus suitable for transmitting digital information to the recording and reproducing apparatus as above.
2. Description of the Related Art
Digital television broadcasting has been started and digital recording and reproducing apparatus for recording and reproducing digital information have been brought to market. In addition, even in the field of package medium such as movie software, package software to be used with this type of apparatus will be developed and practiced in the near future.
The digital recording scheme has an advantage that the quality is not deteriorated or very less degraded in the recording and reproducing process. But in the event that many high-quality copies are prepared and circulated at a site unknown to a copyright holder, there arises a problem that profits cannot be returned to the copyrighters. This is a pending problem for which countermeasures have been discussed in various fields since a case of digital audio tape deck at issue.
For example, JP-A-11-146378 discloses a method of preventing preparation of high-quality copies by degrading the quality in advance of digitally recording information.
U.S. Pat. No. 5,896,454 discloses a method of adding copy control information of 2 bits to data information. In the method, any one of copy inhibition, copy approval and copy approval for only one generation is selected of volition of copyright holders or information planners to control the operation of a recording apparatus. The recording apparatus does not perform recording operation if copy inhibition is selected but performs recording operation if copy approval is selected. With copy approval for only one generation selected, the recording apparatus rewrites this control information into information for inhibiting any more copies and then operates to record.
In other words, the copy control information useful for the information data planner to control copying operation by users has been proposed. For example, codes of “copy never” (copy inhibition), “copy one generation” (for permitting only one copy), “no more copies” (data once copied through “copy one generation” is not permitted for more copies) and “copy free” (approval of copying) are set in a header part of data or a watermark (WM), very difficult to detect, is embedded in an image. The above expedient is expected to solve the problem without inflicting a one-sided loss on the copyright holders or users.
But, even in case the stringent inhibition, for example, “copy never” is imposed, there is obviously a spontaneous need for temporarily recording information on, for example, a hard disc of a receiving apparatus and playing back the information and therefore, with a view of mitigating a loss on the side of users, a means for this purpose is necessary. At that time, it must also be considered to mitigate a loss on the side of copyright holders.
More particularly, when a visitor comes accidentally while the copy control information being set to “copy never” in broadcasting, a user in question disadvantageously looses a chance of playing back a broadcast program. Under the circumstances, JP-A-2000-149417 discloses a method of eliminating such a problem by using a means “temporary recording” even when the copy control information designates “copy never”. According to the method, information is once recorded physically on a recording medium and a limit of 90 minutes for instance is set to the period for reproduction and playback and the information is erased after a playback or at the termination of the period. In other words, the recording is not for long-term conservation and multipurpose utilization but simply permits the broadcasting to be equivalently played back 90 minutes later. Since the information on the recording medium does not remain for a long time, the aforementioned inconvenience of users can be eliminated without inflicting an unprofitableness to the copyright holders. The temporary recording is, because of its nature, carried out frequently by using a hard disc recorder built in the receiving apparatus.